On Thu, 31 Jul 2003 17:18:34 GMT, "Travis Jordan" wrote:

Peter wrote:
I'd like to find out whether there is any "standard" to the wiring
between home thermostats and the HVAC equipment.

The thermostats in my house are connected to the HVAC units in the
basement via a 5 conductor cable. Yellow, green, white, red, blue.

The blue is not connected. I *assume* that two of the other four are
the main on/off and the other two are for the fan on/auto switch.
Can I tell by color which is which or do I have to open up the
thermostat and look?

Thanks.

Peter

Most installers adopt the commonly used 'standard' wire color code.
Here's a sample of some typical usage:

R Red - Power 24 VAC transformer
C Black/Blue - Common of 24 VAC transformer
W White - Primary heat call relay
E Brown - Emergency heat relay
Y Yellow - Primary cool call relay
G Green - Fan relay
O Orange - Change-over to cool relay
B Blue - Change-over relay to heat relay

Here's as much as you will ever want to know about the various
manufacturer's equipment-to-thermostat connections:

http://hbctechlit.honeywell.com/tech...0s/70-6627.pdf

So, which two wires are for the fan On function. Green is one, which is
the other?

In other words, if I wanted to run a jumper between two of the terminals
to force the fan to be On all the time (as if I put the fan switch in the
On position), which two terminals would it be? I assume one is where the
green wire is connected. Which is the other?

Peter

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